Medical device having linear to rotation control

ABSTRACT

A medical instrument converts linear movement of a shaft at a proximal end of the instrument to a rotational movement of an end effector of the instrument. According to one embodiment, the medical instrument includes an end effector formed of a snare loop connected to a shaft that is located within a sleeve. Once the sleeve is located near a desired location within a patient, the snare loop may be rotationally positioned with linear movement of the shaft by the operator. The shaft is formed with a threaded portion that matches threads formed in a torque transmitter element fixed within the sleeve. Linear movement of the shaft through the torque transmitter element causes the shaft to rotate. The medical instrument may also include a pivot connector for reducing torque build-up of the shaft and/or a clutch assembly for restricting controlled rotation of the snare loop to only one direction.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/208,468, filed Jun. 2, 2000, and U.S. ProvisionalApplication No. 60/253,723, filed Nov. 29, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to medical retrieval orelectro-cutting devices, and more particularly to a medical retrieval orelectro-cutting device including a rotatable end effector.

[0004] 2. State of the Art

[0005] Medical retrieval or electro-cutting devices are used for anumber of purposes within the body cavity. For example, a medicalretrieval device in the form of a snare instrument is used for theendoscopic removal of hypertrophic tissue growths or polyps within abody cavity. Snare instruments generally include an elongated tubularmember, such as a catheter sheath, a wire or shaft extending through thetubular member, and an elastic wire (e.g., stainless steel or Nitinol)forming a loop movable distally and proximally within the tubularmember. The loop can be opened by moving the loop beyond the distal endof the tubular member and closed by retraction into the tubular member.Loop opening and closing is effected by movement of the shaft relativeto the tubular member. A handle is provided at the proximal end of theinstrument to facilitate this movement.

[0006] With the loop of the snare instrument in a retracted position,the distal end of the instrument is inserted through an endoscope intothe gastrointestinal tract and moved toward a polyp or other tissuegrowth which is identified for removal from the wall of the tract. Thehandle of the instrument is then operated to expand the loop of thesnare and an attempt is made to maneuver the loop to surround the polyp.If successful, the loop is then constricted about the polyp to exciseit.

[0007] It will be appreciated that manipulation of the loop of the snareinstrument about the polyp is a difficult, and sometimes unattainable,task. The expanded snare loop often lies in a plane which is notconducive for maneuvering about the target polyp. Therefore, the desiredpolyp retrieval often requires extensive effort, including attempts torotate the catheter sheath to orientate the snare loop about the polyp.Rotation of the catheter sheath, however, often moves the snare loop outof position or causes detrimental whipping of the snare loop during theprocedure.

SUMMARY OF THE INVENTION

[0008] The objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

[0009] To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the inventioncomprises a medical instrument including a sleeve having a proximal endand a distal end, a shaft at least partially received in the sleeve andincluding a proximal end and a distal end, an end effector connected tothe shaft distal end, and a shaft portion having a discontinuous outersurface profile, a handle assembly attached to the proximal end of thesleeve and the proximal end of the shaft, the handle assembly capable ofcontrolling at least a linear movement of the shaft, and a torquetransmitter element fixedly located within the sleeve and having anopening extending therethrough for receiving the shaft portion, asurface of the opening having a discontinuous profile for mating withthe discontinuous profile of the shaft portion so that a linear movementof the shaft causes a rotational motion of the end effector.

[0010] To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the inventionfurther comprises a medical instrument including a sleeve having aproximal end and a distal end, a shaft formed of at least a first andsecond shaft segments, the shaft at least partially received in thesleeve and including a proximal end and a distal end, an end effectorconnected to the shaft distal end, and a shaft portion having adiscontinuous outer surface profile, a handle assembly attached to theproximal end of the sleeve and the proximal end of the shaft, the handleassembly capable of controlling at least a linear movement of the shaft,a torque transmitter element fixedly located within the sleeve andhaving an opening extending therethrough for receiving the shaftportion, a surface of the opening having a discontinuous profile formating with the discontinuous profile of the shaft portion so that alinear movement of the shaft causes a rotational motion of the endeffector, and a pivot connector located within the sleeve and proximalto the torque transmitter element, the pivot connector including ahousing for receiving a distal end of a first shaft segment and aproximal end of the second shaft segment, the housing substantiallyrestricting relative linear movement of the first and second shaftsegments while allowing unrestricted relative rotational movement of thefirst and second shaft segments.

[0011] To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the inventionfurther comprises a medical instrument including a sleeve having aproximal end and a distal end, a shaft formed of at least a first andsecond shaft segments, the shaft at least partially received in thesleeve and including a proximal end and a distal end, an end effectorconnected to the shaft distal end, and a shaft portion having adiscontinuous outer surface profile, a handle assembly attached to theproximal end of the sleeve and the proximal end of the shaft, the handleassembly capable of controlling at least a linear movement of the shaft,a torque transmitter element fixedly located within the sleeve andhaving an opening extending therethrough for receiving the shaftportion, a surface of the opening having a discontinuous profile formating with the discontinuous profile of the shaft portion so that alinear movement of the shaft causes a rotational motion of the endeffector, and a clutch assembly located within the sleeve and distal ofthe torque transmitter element, the clutch assembly including a clutchhousing for receiving a distal end of the first shaft segment and aproximal end of the second shaft segment, the housing restrictingcontrolled rotational movement of the end effector to only onerotational direction.

[0012] To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the inventionfurther comprises a method of positioning an end effector of a medicalinstrument at a desired location comprising the steps of positioning asleeve within a patient the desired location, the sleeve includingtherein a shaft having the end effector connected to a distal endthereof; and moving a portion of the shaft in a linear direction througha torque transmitter element to cause rotation of the end effector to adesired rotational position.

[0013] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate several embodimentsof the invention and together with the description serve to explain theprinciples of the invention. In the drawings:

[0015]FIG. 1 is partial cross-section view of the medical device inaccordance with a first embodiment of the present invention;

[0016]FIG. 2 is a partial cross-section view of the torque transmitterelement of the medical device in accordance with the first embodiment;

[0017]FIG. 3 is a partial cross-section view of the medical device inaccordance with a second embodiment of the present invention;

[0018]FIG. 4 is a partial cross-section view of the pivot element of themedical device in accordance with the second embodiment;

[0019]FIG. 5 is a partial cross-section view of the medical device inaccordance with a third embodiment of the present invention; and

[0020]FIG. 6 is a partial cross-section view of the clutch assembly ofthe medical device in accordance with the third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Reference will now be made in detail to embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

[0022]FIG. 1 illustrates a medical device in the form of a medical snareinstrument 10. While the present invention will be described inconnection with a medical snare instrument 10, the invention may beapplied to numerous other devices utilized during endoscopy or othersurgical procedures. For example, the present invention could be appliedwith sphinctertomes or steerable catheters, and any one of a medicalcutting instrument, such as, for example, a medical forceps instrumentor a medical stone basket instrument.

[0023] Snare instrument 10 includes an inner elongated flexible tubularsleeve 12 and an outer elongated flexible tubular sleeve 14. Innersleeve 12 is fixedly secured to a handle assembly (generically shown aselement 13) and includes a proximal end (not shown) and a distal end 16.Inner sleeve 12 may be manufactured by an extrusion process and formedof thermoplastic material such as, for example, Nylon or Polyethylene.Other suitable materials known in the art may be used. A flexible wireor shaft 18 extends through inner sleeve 12, and inner sleeve 12 may besized to fit closely to the wire and thereby eliminate excess play.Outer sleeve 14 also includes a proximal end (not shown) and a distalend 20, and is located outside of inner sleeve 12 so that it is movablerelative to inner sleeve 12. Outer sleeve 14 may be manufactured by anysuitable process and may be formed of any suitable material such asTeflon.

[0024] Shaft 18 is axially movable relative to inner and outer sleeves12, 14 and includes a snare loop 22 mechanically coupled to its distalend 24. As will be discussed in more detail below, the proximal end ofshaft 18 is connected to the handle assembly 13 for allowing the user toreciprocate shaft 18 relative to inner sleeve 12. The handle assembly isalso connected to outer sleeve 14 for reciprocating outer sleeve 14relative to both the inner sleeve 12 and shaft 18. Reciprocation ofouter sleeve 14 relative to shaft 18 results in the snare loop 22 beingcontained within outer sleeve 14 or opened beyond the distal end 20 ofouter sleeve 14. FIG. 1 shows snare loop 22 opened beyond the distal end20 of outer sleeve 14.

[0025] Shaft 18 preferably includes a multifilament twisted and drawn orswaged cable. The filaments of the cable are preferably either stainlesssteel, nickel-titanium alloy, or a combination of the two. As shown inFIG. 2, the twists of cable forming shaft 18 create a discontinuousouter surface profile 26. In one embodiment of the invention, thediscontinuous profile of shaft 18 forms a thread pattern about itsperipheral surface, similar to that of a screw. Shaft 18 can be of othermaterials so long as it includes threads 26 and is flexible enough tobend, yet rigid enough to resist minor compressive forces.

[0026] Snare loop 22 is preferably also formed from a length ofmultifilament twisted and drawn or swaged cable, as described above, oranother resilient cable or wire. The snare loop 22 is attached to thedistal end 24 of the shaft 18, for example, by welding, soldering orcrimping. Alternatively, the shaft may be formed from a resilient cableor wire which has first and second ends proximally twined and anuntwined looped distal portion forming the snare loop; that is, thesnare loop is integral with the shaft. As yet another alternative, thetwo sides of the snare loop may be formed from separate wire or cableelements coupled together at their proximal and distal ends to form thesnare loop therebetween.

[0027] A positioning sleeve 25, or other suitable element, slidablewithin an inner surface 32 of the inner sleeve 12 may be attached aboutthe junction of shaft 18 and snare loop 22. Positioning sleeve 25thereby aids in a ensuring a smooth, aligned movement of shaft 18.Accordingly, positioning sleeve 25 and inner sleeve 12 must be locatedsuch that positioning sleeve 25 does not extend completely beyond distalend 16 of the inner sleeve 12.

[0028] Inner sleeve 12 further includes a torque transmitter element 30(FIG. 2) for converting linear movement of shaft 18 to rotational motionof the snare loop 22. Torque transmitter 30 is fixedly secured to theinner surface 32 of inner sleeve 12 and is generally cylindricallyshaped with a port or opening 34 extending axially therethrough. Openingor port 34 includes a discontinuous surface profile, such as threads 36having a pitch closely matching the outer surface profile or threads 26of shaft 18. Accordingly, because torque transmitter 30 is fixed ininner sleeve 12, the mating of threads 26 of shaft 18 with threads 36 ofport 34 during linear movement of the shaft 18 results in rotation ofshaft 18 and snare loop 22. The pitch of the threads 26 of shaft 18determines the sensitivity and magnitude of the rotation of snare loop22 resulting from reciprocating of shaft 18. According to thisembodiment of the present invention, threads 26 of shaft 18 are sized sothat a maximum axial movement of shaft 18 at the handle assembly 13causes a 360 degree rotation of snare loop 22 in one of a clockwise orcounterclockwise direction. Conversely, maximum axial movement of shaft18 in the opposite axial direction at the handle assembly causes a 360degree rotation of snare loop 22 in the other of a clockwise orcounterclockwise direction. Torque transmitter 30 may be formed of anysuitable material and could be a separate element from the inner sleeve12, or molded into the extrusion of the inner sleeve 12.

[0029] Certain endoscopic applications require injection of contrastmedia or other fluid into the body cavity to, for example, visualize thesurgical site. To allow for injection of such fluid through inner sleeve12, torque transmitter 30 may include small axial holes therethrough, orgrooves in its outer periphery. Torque transmitter 30 also may be formedof porous material that allows fluid to pass to the distal end of thedevice and into the body cavity. Alternatively, outer sleeve 14, asingle lumen sleeve, could be replaced with a double lumen sleeve (notshown). With this configuration, one lumen would include all of theaspects described above and below in connection with outer sleeve 14,and the other lumen would form a passageway for injecting contrast mediaor other fluid to the desired site.

[0030] In a further embodiment of the present invention, a third sleeve(not shown) is included extending parallel to the exterior of outersleeve 14. A distal end of the third sleeve merges with the interiorarea of outer sleeve 14 through a port in outer sleeve 14, the portbeing located between distal end 16 of inner sleeve 12 and distal end 20of outer sleeve 14. With this configuration, the retrieval device can beguided into position at the desired site by inserting a guide wirethrough the third sleeve, through the outer sleeve port, and out distalend 20 of outer sleeve 14. Once the retrieval device is positioned atthe desired site, the guide wire is removed from the third sleeve andthe third sleeve is utilized to inject contrast media or other fluid tothe desired site.

[0031] Handle assembly 13 may include a combined reciprocating controlfor both the outer sleeve 14 and shaft 18. Accordingly, the handleassembly includes a trigger element or other assembly for reciprocatingouter sleeve 14 relative to shaft 18. Thus, activation of the triggerelement causes snare loop 22 to either expand as the outer sleeve isretracted, so that snare loop 22 extends beyond the distal end of outersleeve 14, or retract as outer sleeve 14 is urged over snare loop 22.The handle assembly may also include a thumb controlled element capableof reciprocation within the handle assembly. The thumb controlledelement is directly connected to shaft 18 so that reciprocation of thethumb controlled element reciprocates shaft 18 through torquetransmitter 30, and thereby rotates snare loop 22. A stop or stops maybe included on the handle assembly or shaft 18 indicating thecorrespondence between linear movement of shaft 18 and rotationalmovement of snare loop 22. The handle assembly may also include lockingmechanisms for fixing the position of both or either of shaft 18 andouter sleeve 14.

[0032] The thumb controlled element and shaft 18 may be fixedly securedtogether or the medical device may include a pivot connector forallowing shaft 18 to rotate without requiring rotation of the thumbcontrolled element. As illustrated in FIGS. 3 and 4, a pivot connector40 can connect proximal and distal shaft segments 18 a and 18 b togetherto form shaft 18. Pivot connector 40 may be of any conventionalarrangement and may include, for example, an outer body 42 having a bore44 extending axially therethrough. The proximal and distal ends 46, 48of pivot connector 40 include openings 50, 52 having a diameter smallerthan a diameter of the central part 54 of bore 44. Central part 54 ofbore 44 houses a distal end 56 of proximal shaft segment 18 a and theproximal end 58 of distal shaft segment 18 b. Proximal and distalsegment ends 56 and 58 are each formed with an end element havingdiameters larger that the diameters of openings 48 and 50. Thedifference in diameters prohibits shaft segments 18 a and 18 b frombeing removed from pivot connector 40, but allows relative rotationalmotion between them.

[0033] Accordingly, movement of the proximal shaft segment 18 a in adistal direction causes its end 56 to abut the proximal end 58 of distalsegment 18 b and force distal segment 18 b to move in unison withproximal segment 18 a. Also, movement of proximal shaft segment 18 a inthe proximal direction causes its distal end 56 to abut the proximal end46 of pivot connector 40 and thereby force distal segment 18 b in theproximal direction by its end's abutment against the distal end 48 ofpivot connector 40. Accordingly, pivot connector 40 alleviates torquebuild-up in shaft 18 along the length of the medical device, and allowsan operator to reciprocate shaft 18 at the handle assembly without anyrotational movement

[0034] In accordance with the present invention, distal end 20 of outersleeve 14 may be reduced in diameter (“drawn down”) to match thediameter of inner sleeve 12. The drawn down aspect of outer sleeve 14would provide for improved positioning of snare loop 22 in relation tothe desired polyp.

[0035] A user operating the above described embodiments of the presentinvention inserts the snare instrument 10, for example, into anendoscope located in the colon, utilizes the scope to identify forexcision and retrieval a polyp on the wall of the colon, and maneuversthe distal end of the undeployed snare instrument in the colon to alocation slightly beyond the polyp. The user then actuates the handleassembly of the instrument 10 to cause outer sleeve 14 to be movedproximally relative to the position of snare loop 22 to move the snareloop 22 out of outer sleeve 14. The snare loop 22 extends in axialrelation to the axis of outer sleeve 14 and rests on or adjacent thewall of the colon proximal of the polyp. The snare loop 22 is thenrotated into a desired position by reciprocal movement of the thumbcontrolled element of the handle assembly. The user then preferablyadvances outer sleeve 14, thereby tightly closing snare loop 22 aboutthe polyp so that the polyp is excised. The outer sleeve 14 is thenextended over snare loop 22 with polyp held therein, and the instrument10 is removed from the colon.

[0036] While the snare instrument has been described for use in thegastrointestinal tract, it will be appreciated that it can be usedelsewhere within the body, e.g., the uterus or urinary tract. It willtherefore be appreciated by those skilled in the art that yet othermodifications could be made to the provided invention without deviatingfrom its spirit and scope as claimed.

[0037]FIGS. 5 and 6 illustrate yet another embodiment of the presentinvention. This embodiment is similar to the embodiments describedabove, except the outer sleeve 14 is removed and a clutch assembly 60 isadded. In this embodiment snare loop 22 is configured so that itretracts into the same sleeve 12 that contains shaft 18, rather than anouter sleeve 14. Accordingly, a single reciprocation of shaft 18 canboth rotate snare loop 22 when outside of sleeve 12 and retract snareloop 22 into sleeve 12. Clutch assembly 60 prohibits a rotation of shaft18 from being transferred to snare loop 22 during retraction of thesnare loop 22 into sleeve 12. Allowing a rotation of snare loop 22 onlyduring the advancement of shaft 18 insures that snare loop 22 willmaintain its position on the polyp during retraction of snare loop 22 ina proximal direction and into inner sleeve 12.

[0038] Clutch assembly 60 is located within sleeve 12 distal of torquetransmitter element 30 and pivot connector 40, and includes a clutchbody 62 for receiving a clutch proximal end element 64 connected to adistal end of proximal shaft segment 18 c, and a clutch distal endelement 66 connected to a proximal end of distal shaft segment 18 d.Clutch body 62 may be of any conventional shape and material so long asit securely houses both clutch proximal end element 64 and clutch distalend element 66 and prevents those elements from being removed from body62. For example, as illustrated in FIG. 6, clutch body 62 may be formedin a cylindrical shape with tapering ends 68. Further, clutch body 62 issized to allow shaft segment 18 c to rotate relative to shaft segment 18d. This relative rotation of shaft segments 18 c and 18 d can beprovided by designing clutch body 62 with sufficient clearance to allowboth clutch proximal end element 64 and clutch distal end element 66 torotate within the housing without contacting each other, or by fixedlysecuring clutch distal end element 66 to clutch body 62 and providingsufficient clearance in clutch body 62 for clutch proximal end element64 to rotate within body 62 without contacting clutch distal end element66.

[0039] Clutch proximal end element 64 includes a distal face 70 having agear configuration thereon. Similarly, clutch distal end element 66includes a proximal face 72 having a gear configuration thereon. Thegear configurations are designed so that when they mesh, rotation ofproximal shaft segment 18 c is transmitted to rotation of distal shaftsegment 18 d only in one direction, and not in the other rotationaldirection. This one-way only rotation of distal shaft segment 18 d maybe achieved by any standard unidirectional gearing arrangement. Forexample, distal face 70 of clutch proximal end element 64 could includeat least one sloping protrusion 74. The slope of protrusion 74 providesan increasing thickness of protrusion 74 in the direction of the one-waymovement and ends at a flat gearing face 76 extending perpendicular todistal face 70. Proximal face 72 of clutch distal end element 66includes at least one sloping protrusion 78 similar and equal in numberto that found on the clutch proximal end element 64. The slope ofprotrusion 78 of proximal face 72, however, provides an increasingthickness of protrusion 78 in the direction opposite of the one-waymovement so that a flat gearing face 80 is formed to mesh with flatgearing face 76 only when flat gearing face 76 is rotated in the one-waydirection.

[0040] In accordance with the embodiment of FIGS. 5 and 6, linearmovement of shaft 18 in the distal direction at a handle assembly 13 isconverted to linear and rotational movement at torque transmitterelement 30. This conversion causes proximal shaft segment 18 c andclutch proximal end element 64 to rotate and move distally within clutchbody 62. Clutch proximal end element 64 moves distally within clutchbody 62 until it contacts clutch distal end element 66. Upon contactwith clutch distal end element 66, clutch proximal end element 66continues to rotate relative to shaft segment 18 d until flat gearingface 76 mates with flat gearing face 80. Upon mating of flat gearingfaces 76, 80 shaft segments 18 c and 18 d rotate in unison in thedirection of one-way movement, and thereby allow rotation of snare loop22 to its desired rotational position. Once the target tissue is withinsnare loop 22, shaft 18 is retracted so that snare loop 22 is tightlyclosed about the polyp and snare loop 22 is urged into sleeve 12. Thisretraction of shaft 18 causes clutch proximal end element 64 to move ina proximal direction out of contact with clutch distal end element 66.Accordingly, rotation of proximal shaft segment 18 c caused by torquetransmitter element 30 during retraction of shaft 18 in the proximaldirection does not cause rotation of distal shaft segment 18 d and snareloop 22. Further, even before complete separation of clutch end elements64 and 66, rotation of proximal shaft segment 18 c during retraction ofshaft 18 would not be transferred to segment 18 d, but would only resultin sliding contact of slope surfaces 82 and 84 of end elements 64 and66.

[0041] As noted above, the embodiment of FIGS. 5 and 6 of the presentinvention includes a torque transmitter 20 and pivot connector 40 havingthe features detailed above. The medical device of FIGS. 5 and 6 mayalso include a handle assembly as described above, but without areciprocating control for an outer sleeve. Further, the positioningsleeve 25 and additional sleeve or lumen described above could beincorporated into the embodiment of FIGS. 5 and 6.

[0042] Other embodiments of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. For example, as noted above, thesnare loop described above could be replaced with a stone basket,cutting device, or other end effector requiring rotational movement.Further the outer surface of shaft 18 can be of any profile that willcause rotation of the shaft when reciprocated through the torquetransmitter 40.

What is claimed is:
 1. A medical instrument comprising: a sleeve havinga proximal end and a distal end; a shaft at least partially received inthe sleeve and including a proximal end and a distal end, an endeffector connected to the shaft distal end, and a shaft portion having adiscontinuous outer surface profile; a handle assembly attached to theproximal end of the sleeve and the proximal end of the shaft, the handleassembly capable of controlling at least a linear movement of the shaft;and a torque transmitter element fixedly located within the sleeve andhaving an opening extending therethrough for receiving the shaftportion, a surface surrounding the opening having a discontinuousprofile for mating with the discontinuous profile of the shaft portionso that a linear movement of the shaft causes a rotational motion of theend effector.
 2. The medical instrument of claim 1, wherein thediscontinuous outer surface profile of the shaft portion forms a threadpattern, and the discontinuous profile of the opening surface of thetorque transmitter element forms a thread pattern for mating with thethread pattern of the shaft portion.
 3. The medical instrument of claim1, further including stops for limiting the linear movement of the shaftso as to restrict the amount of rotation of the end effector.
 4. Themedical instrument of claim 1, wherein the torque transmitter element isaffixed to the sleeve and includes at least one additional openingextending therethrough for allowing fluid to pass through the torquetransmitter element.
 5. The medical instrument of claim 1, wherein thedistal end of the shaft includes a positioning sleeve having an outerdiameter slightly smaller than an inner diameter of the distal end ofthe sleeve, the positioning sleeve slidingly received in the distal endof the sleeve for centering the shaft about the distal end of thesleeve.
 6. The medical instrument of claim 1 wherein the shaft is formedof a single shaft segment so that linear movement of the shaft in aproximal direction and in a distal direction each results in rotationalmotion of the end effector.
 7. The medical instrument of claim 1,further including a pivot connector for substantially restrictingrelative linear movement between segments of the shaft while allowingunrestricted relative rotational movement between segments of the shaft.8. The medical instrument of claim 7, further including a clutchassembly for restricting controlled rotational movement of the endeffector to only one rotational direction.
 9. The medical instrument ofclaim 1, further including a clutch assembly for restricting controlledrotational movement of the end effector to only one rotationaldirection.
 10. The medical instrument of claim 9, wherein the clutchassembly includes a gear configuration for interlocking shaft segmentsin only one rotational direction.
 11. The medical instrument of claim 1,wherein the end effector includes a snare loop.
 12. The medicalinstrument of claim 11, wherein the sleeve is an inner sleeve and theinstrument includes an outer sleeve, the outer sleeve capable ofrelative linear movement with the shaft to cover and uncover the snareloop.
 13. A medical instrument comprising: a sleeve having a proximalend and a distal end; a shaft formed of at least a first shaft segmentand a second shaft segment, the shaft at least partially received in thesleeve and including a proximal end and a distal end, an end effectorconnected to the shaft distal end, and a shaft portion having adiscontinuous outer surface profile; a handle assembly attached to theproximal end of the sleeve and the proximal end of the shaft, the handleassembly capable of controlling at least a linear movement of the shaft;a torque transmitter element fixedly located within the sleeve andhaving an opening extending therethrough for receiving the shaftportion, a surface surrounding the opening having a discontinuousprofile for mating with the discontinuous profile of the shaft portionso that a linear movement of the shaft causes a rotational motion of theend effector; and a pivot connector located within the sleeve andproximal to the torque transmitter element, the pivot connectorincluding a housing for receiving a distal end of the first shaftsegment and a proximal end of the second shaft segment, the housingsubstantially restricting relative linear movement between the first andsecond shaft segments while allowing unrestricted relative rotationalmovement between the first and second shaft segments.
 14. The medicalinstrument of claim 13, wherein the discontinuous outer surface profileof the shaft portion forms a thread pattern, and the discontinuousprofile of the opening surface of the torque transmitter element forms athread pattern for mating with the thread pattern of the shaft portion.15. The medical instrument of claim 13, wherein the distal end of thefirst shaft segment and the proximal end of the second shaft segmenteach include an end element having a diameter greater than a diameter ofthe shaft.
 16. The medical instrument of claim 13, wherein the endeffector includes a snare loop.
 17. The medical instrument of claim 16,wherein the sleeve is an inner sleeve and the instrument includes anouter sleeve, the outer sleeve capable of linear movement to cover anduncover the snare loop.
 18. The medical instrument of claim 13, furtherincluding a clutch assembly for restricting controlled rotationalmovement of the end effector to only one rotational direction.
 19. Themedical instrument of claim 18, further including a third shaft segmentlocated distal of the second shaft segment, wherein the clutch assemblyincludes a gear configuration for interlocking the second and thirdshaft segments in only one rotational direction.
 20. A medicalinstrument comprising: a sleeve having a proximal end and a distal end;a shaft formed of at least a first shaft segment and a second shaftsegments, the shaft at least partially received in the sleeve andincluding a proximal end and a distal end, an end effector connected tothe shaft distal end, and a shaft portion having a discontinuous outersurface profile; a handle assembly attached to the proximal end of thesleeve and the proximal end of the shaft, the handle assembly capable ofcontrolling at least a linear movement of the shaft; a torquetransmitter element fixedly located within the sleeve and having anopening extending therethrough for receiving the shaft portion, asurface surrounding the opening having a discontinuous profile formating with the discontinuous profile of the shaft portion so that alinear movement of the shaft causes a rotational motion of the endeffector; and a clutch assembly located within the sleeve and distal ofthe torque transmitter element, the clutch assembly including a clutchhousing for receiving a distal end of the first shaft segment and aproximal end of the second shaft segment, the housing restrictingcontrolled rotational movement of the end effector to only onerotational direction.
 21. The medical instrument of claim 20, whereinthe discontinuous outer surface profile of the shaft portion forms athread pattern, and the discontinuous profile of the opening surface ofthe torque transmitter element forms a thread pattern for mating withthe thread pattern of the shaft portion.
 22. The medical instrument ofclaim 20, wherein the end effector includes a snare loop.
 23. Themedical instrument of claim 22, wherein the sleeve is an inner sleeveand the instrument includes an outer sleeve, the outer sleeve capable ofrelative linear movement with the shaft to cover and uncover the snareloop.
 24. The medical instrument of claim 20, further including a pivotconnector for substantially restricting relative linear movement betweenthe first and second segments of the shaft while allowing unrestrictedrelative rotational movement between the first and second segments ofthe shaft.
 25. The medical instrument of claim 24, further including athird shaft segment located proximal the first shaft segment, whereinthe distal end of the third shaft segment and the proximal end of thefirst shaft segment each include an end element having a diametergreater than a diameter of the shaft.
 26. A method of positioning an endeffector of a medical instrument at a desired location comprising thesteps of: positioning a sleeve within a patient at the desired location,the sleeve including therein a shaft having the end effector connectedto a distal end thereof; and moving a portion of the shaft in a lineardirection through a torque transmitter element to cause rotation of theend effector to a desired rotational position.
 27. The method of claim26, wherein the end effector includes a snare loop.
 28. The medicalinstrument of claim 27, wherein the sleeve is an inner sleeve and theinstrument includes an outer sleeve, the outer sleeve capable ofrelative linear movement with the shaft to cover and uncover the snareloop.